JPH01191416A - Pattern forming method - Google Patents

Abstract

PURPOSE:To obtain a high accuracy and a high productivity by forming a plurality of charged beam positioning marks when a pattern is transferred previously by an optical reduction projecting exposure device, and then forming a desired pattern by a charged beam lithography device by utilizing the marks. CONSTITUTION:A pattern 3 having a relatively large size is first exposed by an optical reduction projection on a wafer 1 at each unit chip. In this case, a plurality of alignment marks 2 for a charged beam lithography are formed at respective exposure fields further finely divided from each unit chip. Then, the charged beam lithography 4 is conducted with the marks, thereby forming a fine pattern. Thus, even if difference of exposure distortions occurs between an optical reduction projection exposure device and a charged beam lithography device, the exposure by the lithography device is conducted by alterning the mark at each fine region in the chip. Accordingly, the influence of the exposure distortions of the both is extremely reduced, and no pattern error which becomes a problem in practice does not occur.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of forming an element pattern.

[Conventional technology]

2. Description of the Related Art In recent years, semiconductor devices have become highly integrated and miniaturized, and charged beam lithography devices or optical reduction projection exposure devices that have highly accurate transfer performance are used to form device patterns on semiconductor wafers. FIG. 3 is a schematic configuration diagram of a charged beam lithography apparatus, in which the surface of a wafer 1 placed on a stage 11 is irradiated with an electron or ion beam from an electron gun 12 that is focused and deflected by an electron lens 13. The pattern is formed by FIG. 4 is a schematic configuration diagram of an optical reduction projection exposure apparatus, in which a pattern formed on a mask 14 is imaged on the surface of the wafer 1 by an optical lens 17 while limiting the irradiation area of the light source 16 with a shielding Fi 15. Pattern formation is performed using

[Problem to be solved by the invention]

In the conventional package forming method described above, the charged beam lithography system shown in Fig. 3 can form very fine patterns of around 0.3 μm, but it not only takes a lot of time for lithography but is also very expensive. Since it is a simple device, there is a problem in terms of productivity.

Further, although the optical reduction projection exposure apparatus shown in FIG. 4 has high precision and high productivity, it has a problem in that it cannot form fine patterns of around 0.3 μm.

Therefore, in order to compensate for each other's shortcomings, a so-called hybrid exposure apparatus, which combines a charged beam lithography apparatus and an optical reduction projection exposure apparatus, has been proposed. That is, in this apparatus, as shown in FIG. 5(a), pattern formation is performed by using an alignment mark 2A provided for each unit chip of the wafer for both charged beam writing and optical reduction projection exposure.

However, in this apparatus, as shown in FIG. 5(b), the exposure distortion A (shown by the broken line) present in the charged beam lithography system and the exposure distortion B (shown by the solid line) present in the optical reduction projection exposure system are normal. Since they do not match, there is a problem in that errors tend to occur between the two patterns, resulting in a decrease in pattern formation accuracy.

An object of the present invention is to provide a pattern forming method that can improve the pattern forming accuracy in the above-mentioned hybrid exposure apparatus and achieve high accuracy and high productivity.

[Means for Solving the Problems] In the pattern forming method of the present invention, a pattern is first transferred using an optical reduction projection exposure device, and at the same time, a plurality of positioning marks for a charged beam are formed in each exposure field, and then the positioning marks are A desired pattern is drawn by a charged beam drawing device using the mark to obtain a desired pattern.

[Function] In the above-mentioned method, the pattern formed by the optical reduction projection exposure device is subjected to writing using a charged beam drawing device for each fine region, so that exposure distortion that follows the exposure distortion of the optical reduction projection exposure device is generated. A charged beam writing pattern is formed.

[Example] Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a diagram for explaining a method according to an embodiment of the present invention, and FIG. 1(a) is a plan view of the entire wafer Φ.

FIG. 5B is a plan view of the unit chip after optical reduction projection exposure, and FIG. 1C is a plan view of the unit chip after charged beam drawing.

In this pattern forming method, first, as shown in FIG. 1(a), a relatively large pattern 3 is exposed on a wafer 1 for each unit chip using an optical reduction projection device. At this time, as shown in FIG. 1(b), a plurality of alignment marks 2 for IT beam drawing are formed for each exposure field obtained by further subdividing each unit chip. This alignment mark 2 for charged beam drawing is 0.5 m both vertically and horizontally.
It is preferable to arrange them at intervals of m to 2 cylinders. Of course, the optimum spacing is the size of the exposure field (typically 6 mm-14
mm).

Then, as shown in FIG. 1C, charged beam writing 4 is performed using the charged beam alignment mark 2 to form a fine pattern.

Therefore, in this pattern forming method, even if a difference in exposure distortion as shown in FIG. 5(b) occurs between the optical reduction projection exposure device and the charged beam lithography device, the exposure by the charged beam lithography device Since the alignment marks are changed for each fine region within a unit chip, the influence of exposure distortion on both is extremely small, and pattern errors that pose a practical problem do not occur.

This makes it possible to realize suitable pattern formation that takes advantage of both the high productivity of the optical reduction projection exposure apparatus and the high precision of the charged beam lithography apparatus.

FIG. 2 is a diagram for explaining another embodiment of the present invention, and FIGS.
) is a similar figure.

In this embodiment, as shown in FIG.
As shown in FIG. 3B, a plurality of alignment marks 2 are formed for each unit chip 3, but here the alignment marks 2 are formed only at necessary locations within the unit chip.

For other locations, data on designated alignment marks that have been prepared as alignment standards for each wafer or chip are used to align the data as shown in Figure 2(c).
Charged beam writing 4 is performed as shown below.

By doing this, only the areas where exposure distortion between optical reduction projection exposure and charged beam writing is likely to be a problem are corrected, and data for other marks is drawn using representative mark data, reducing drawing time. It has the advantage that it can be quantified.

〔Effect of the invention〕

As explained above, the present invention first forms a plurality of positioning marks for a charged beam when transferring a pattern using an optical reduction projection exposure device, and then uses the positioning marks to draw a desired pattern using a charged beam drawing device. Since the pattern is drawn using a photoreduction projection exposure device, the charged beam lithography device is used to write each minute area within the pattern formed by the photoreduction projection exposure device, and the exposure distortion caused by the charged beam drawing follows the exposure distortion caused by the photoreduction projection exposure. In this way, both exposure distortions are automatically corrected to be as small as possible, resulting in the effect that pattern transfer accuracy can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a pattern forming method according to an embodiment of the present invention; FIG. 1(a) is a plan view of a wafer, and FIG.
) is an enlarged plan view of the unit chip at the time when optical reduction projection exposure is completed, FIG. The diagrams are for explaining the method, and the figures (a) to (C) are similar to Figures 1 (a) to (C), respectively, and Figure 3 is a schematic diagram of a general charged beam drawing device. Fig. 4 is a schematic diagram of a general optical reduction projection exposure apparatus, Fig. 5 is a diagram for explaining the problems of the conventional method, and Fig. 4 (a) is a plan view of a wafer;
FIG. 2B is a plan view of exposure distortion in a unit chip. 1... Wafer, 2... Alignment mark, 3...
- Optical reduction exposure pattern, 4... Charged beam drawing pattern, 11... Stage, 12... Electron gun, 13...
・Electronic lens, 14... mask, 15... shielding plate,
16...Light source, 17...Optical lens. Figure 1 (a) (b) (C) Figure 2 (a) (b) (C)

Claims (1)

[Claims] 1. A charged beam writing device that scans a charged beam to draw a pattern on a semiconductor wafer and an optical reduction projection exposure device that uses an optical lens to reduce and transfer a mask pattern onto the semiconductor wafer are used in combination to write a pattern on a semiconductor wafer. In this method, a pattern is first transferred using an optical reduction projection exposure device, and at the same time, a plurality of positioning marks for a charged beam are formed in each exposure field, and then the positioning marks are used to transfer a pattern to a charged beam writing device. A pattern forming method characterized in that a desired pattern is obtained by drawing a desired pattern.